Reddit reviews The Bag On Line Adventures:The Second Stage Turbine Blade #1

There are a few places you could start: The Afterman, the Year of the Black Rainbow novel, or the Amory Wars Second Stage comics.

I'd recommend starting with the Amory Wars Second Stage comics. Keep in mind, you'll want The Amory Wars comics, since they tell the complete story for Second Stage and In Keeping Secrets so far. There's also The Bag.On.Line comics, which were only a couple of issues before they were scrapped. If you decide to pursue them for a collection, expect to pay a bit of money for them.

Following that, you can continue the Amory Wars into In Keeping Secrets.. That's the latest album that's been adapted for those comics, but Claudio is currently writing the Amory Wars versions of Good Apollo 1 and 2.

If you feel like getting a very brief and confusing telling of Good Apollo 1, there's an old graphic novel that was released for it. Again, though, it will run you a bit of money, and while the art style's cool, it doesn't convey the story well and is quite short. For the time being, you'll have better luck finding bits and pieces of the Good Apollo story clued together across the internet and interviews.

You can then go back to the Year of the Black Rainbow novel, which tells the story of Coheed and Cambria's creation. It's pretty self-contained, though it does have a few references that will stick out if you're familiar with the later story.

The Afterman is only loosely connected to the Amory Wars, as it takes place long before Year of the Black Rainbow and expands on some of the unexplained concepts of the universe. Deluxe editions of the album contained artwork and brief explanations of the songs by Claudio, and u/TheElitist921 scanned and uploaded the explanations on the sub. Here's his post for Ascension, and here's the link to Descension.

Happy reading!

Edit: Bonus! u/DefiantLion also gave a synopsis/interpretation of the story to My Brother's Blood Machine over at r/TheFence.

If this is the one you have, then yeah, the $500-1000 is what it'd go for signed provided it's in a proper sleeve and condition etc.